矩形通道内气膜出流对内换热的影响规律

研究对象为矩形通道,包括2个直肋和9个气膜孔,主要研究气膜的出流比、开孔率对通道内换热的影响,温度场的测量采用了热色液晶测温技术.实验发现气膜出流对换热有强化作用,气膜孔对通道平均换热影响也与其在肋间的位置有关,其中肋后孔的影响最大.在不同的雷诺数下,开一个气膜孔时,出流比在6%~8%之间通道壁面内换热效果最好,低雷诺数下增强换热的效果显著;研究孔边的换热规律发现,在孔下游换热明显增强,从孔边到下游5倍孔直径处,强化换热比在1.1倍以上;此外还研究了开孔率对增强换热的影响规律. 

Film bleeding on internal cooling in rectangular channel

An experimental study was made to obtain heat transfer data in a rectangular channel with two ribs and nine holes.The objectives were to investigate the effect of mass flow ratios and bleed holes area ratio on internal cooling.Test was performed with single bleed hole as well as with multiple holes.Steady-state heat transfer coefficients were obtained using thermochromic liquid crystal.The heat transfer enhancement was observed to largely depend on the placement of bleed hole on the inter-ribs surface.It was found that the area-averaged Nusselt number was enhanced more by placing the bleed hole behind the rib.The best enhancement occurred between 6% and 8%.The heat transfer of effective was improved obviously when the Renolds number was low relatively.Some conclusion can be obtained that the heat transfer was enhanced at the regions from the edge of holes to downstream section.The influence of area flow ratio was also tested.It was found that the best area flow ratio was about 2.5%~3.0%.